The broad objectives of this research are to identify physiological and dietary factors significant in the maintenance of binge eating, a major public health concern in both normal weight and obese individuals. This research also aims to improve current methods of treatment for binge eating and to generate additional strategies for treatment. Protein is more satiating than carbohydrate or fat over the short-and long-term. Protein is one of the most potent stimulant of two satiety agents, cholecystokinin (CCK) and glucagon. Bulimia nervosa (BN) patients and obese patients with binge-eating disorder (BED) may have an impaired satiety response involving the insufficient secretion of CCK. This research aims to test the hypothesis that the administration of protein supplements will reduce binge eating and restore impaired satiety signals in BN and BED patients, while binge eating and satiety signals will not be changed by carbohydrate supplements. It is predicted that during a two-week period of supplementary protein intake, patients with BN and BED will report fewer and smaller binge-eating episodes and less hunger and will consume less at an ad libitum test meal than during supplementary carbohydrate intake. It is also predicted that high-protein meals will produce higher blood levels of glucagon and CCK in patients than high-carbohydrate meals.